Interim Report on Benchmarking FFT Libraries on High Performance Systems

The Fast Fourier Transform (FFT) is used in many applications such as molecular dynamics, spectrum estimation, fast convolution and correlation, signal modulation, and many wireless multimedia applications. FFTs are also heavily used in ECP applications, such as EXAALT, Copa, ExaSky-HACC, ExaWind, WarpX, and many others. As these applications’ accuracy and speed depend on the performance of the FFTs, we designed an FFT benchmark to mea- sure performance and scalability of currently available FFT packages and present the results from a pre-Exascale platform. Our benchmarking also stresses the overall capacity of system interconnect; thus, it may be considered as an indicator of the bisection bandwidth, communication contention noise, and the software overheads in MPI collectives that are of interest to many other ECP applications and libraries.

This FFT benchmarking project aims to show the strengths and weaknesses of multiple FFT libraries and to indicate what can be done to improve their performance. In particular, we believe that the benchmarking results could help design and implement a fast and robust FFT library for 2D and 3D inputs, while targeting large-scale heterogeneous systems with multicore processors and hardware accelerators that are a co-designed in tandem with ECP applications. Our work involves studying and analyzing state-of-the-art FFT software both from vendors and available as open-source codes to better understand their performance.